Velocity-dependent dissipation from free vortices and bound vortex pairs below the Kosterlitz-Thouless transition

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · Physical Review (Section) B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.40.6684· OSTI ID:5474038

Gillis, K A; Volz, S M; Mochel, J M ^[1]

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1. Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (US)

We have developed a model for the onset of nonlinear dissipation in thin superfluid helium films below the static transition temperature ({ital T}{sub KT}) by extending the linear response theory of Ambegaokar, Halperin, Nelson, and Siggia to include flow velocity. Contributions from both vortex pairs and free vortices are included, the relative contributions of which are controlled by two weakly coupled adjustable parameters: the vortex diffusivity {ital D} and a free vortex creation time {tau}{sub {ital f}}. The model does not predict a critical velocity in the usual sense except at {ital T}=0; however, we define a characteristic velocity for the onset of nonlinear dissipation to compare with experiments. At {ital T}=0 we find a critical velocity given by the Feynman criterion, where the frequency-dependent diffusion length coincides with the zero in the vortex pair energy. Applications of this model to experiments with ac and dc flows are discussed.

• OSTI ID: 5474038
• Journal Information: Physical Review (Section) B: Condensed Matter; (USA), Journal Name: Physical Review (Section) B: Condensed Matter; (USA) Vol. 40:10; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRITICAL VELOCITY
DISSIPATION FACTOR
ENERGY
EVEN-EVEN NUCLEI
FILMS
FLUIDS
FREE ENERGY
HELIUM 4
HELIUM II
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
PHYSICAL PROPERTIES
QUANTUM FLUIDS
STABLE ISOTOPES
SUPERFLUIDITY
THERMODYNAMIC PROPERTIES
THIN FILMS
TRANSITION TEMPERATURE
VELOCITY